Elle's Joseph Hooper interviews anthropologist Helen Fisher, who "has crunched the numbers" and cracked the code of love. By studying the user base of Chemistry.com, Fisher determined that our personalities — and who we're attracted to — can be divided into four categories based on testosterone, estrogen, dopamine and serotonin:

The Explorer, defined by high dopamine activity, is adventurous, novelty-seeking, creative. The Builder, with high serotonin activity, is cautious, conventional, managerial. The Director, pumped up with testosterone, is aggressive, single-minded, analytical. The Negotiator, more estrogen-influenced, is empathetic, idealistic, a big picture thinker.

According to Fisher, Explorers love Explorers, Builders love Builders, and Directors and Negotiators love one another. By giving this wisdom to the masses (in her book Why Him? Why Her?), Fisher says "we're trying to do some pre-selecting for you don't have to kiss a lot of frogs." She continues:

People will always make their own mistakes. What I hope to do is enable us to make fewer of them and understand that sometimes human nature is working against us. Sometimes we fall in love with somebody who will probably never love us, for reasons having nothing to do with us but with their own mind-set, their chemistry.

But is dividing the human race into four categories really going to keep us from doing this? People have been studying personality typessince the 1920s if not before, and online personality tests have been around since the nineties (anyone who ever killed time taking Spark Tests probably remembers being branded a "pizza boy" or, worse, a "pure mountain stream"). Still, people somehow manage to get their hearts broken! How? Perhaps because dividing people into four, or five, or even ten categories is always going to be reductive, because lots of relationships work when it seems they shouldn't, or don't work when it seems they should, and because, as much as we may like to read other people's advice about love, we don't really like to take it. The Laws Of Attraction [Elle]